Removal of swirl artifacts from celp-based speech coders

Details Removal of swirl artifacts from celp-based speech coders Removal of swirl artifacts from celp-based speech coders

1996-10-21

1997-05-27

MacDonald, Allen R.

395 228, 395 235, 395 217, G10L 900, G10L 506

Patent

active

056339828

ABSTRACT:
The perception of speech processed by a CELP based coder, such as a VSELP coder, when operating in noisy background conditions is improved by removing swirl artifacts during silence periods. This is done by removing the low frequency components of the input signal when no speech is detected. A speech activity detector distinguishes between a periodic signal, like speech, and a non-periodic signal, like noise by using most of the VSELP coder internal parameters to determine the speech or non-speech conditions. To prevent the VSELP coder from determining pitches for non-periodic signals, a high pass filter is applied to the input signal to remove the pitch information for which the VSELP coder searches.

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IEEE Transactions on Speech and audio Processing; McCree et al., "A new mixed excitation LPC vocoder", pp. 593-596; May 1991.

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